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Federal Register / Vol. 86, No. 108 / Tuesday, June 8, 2021 / Notices TABLE 8DISTANCES AND AREAS OF HARASSMENT ZONES FOR PILE DRIVING AND DRILLINGContinued Level A harassment Activity
Number of strikes/pile or duration
Pile size, type, and rate
Number of days
HF cetacean Dist.
m
Bedrock drilling for blast charges.

4.5-inch 1,580 holes ..

12 hr/day

Dist.
m
Area km2

130

7

Level B harassment Phocid
0.000153

Dist.
m
Area km2

4.3

0.000058

Area km2

12,023

0.418

0.418 km2 is the maximum ensonified area in the project area for pile driving and drilling due to landmass interception of sound propagation.

TABLE 9DISTANCES AND AREAS OF HARASSMENT ZONES FOR BLASTING
Level A PTS onset harassment 1

Blasting events and charge
Blasting days
530 blasts per event, 120-lb charge per blast event, 150 blast events.

130 12 events/
day.

Level B behavioral harassment
Non-auditory injury gastrointestinal tract
Harbor porpoise distance to 155
dB SELcum threshold/area of ZOI

Phocids distance to 185 dB SELcum threshold/area of ZOI

Harbor porpoise distance to 135
dB SELcum threshold/area of ZOI

Phocids distance to 165 dB SELcum threshold/area of ZOI

Phocid/harbor porpoise distance to 237 dB peak pressure threshold/
area of ZOI
onset of effect
Phocid/harbor porpoise distance to 243 dB peak pressure threshold/
area of ZOI
injury
1,007 m/0.335
km2.

110 m/0.01978
km2.

2,131 m/0.335
km2.

577 m/0.27636
km2.

9 m/0.000254 km2

5 m/0.00008 km2

0.335 km2 is the maximum ensonified area for blasting in the project area due to landmass interception of sound propagation.
1 Distance to 202 dB SPL
peak threshold for harbor porpoises is 19 m, and to 218 dB SPLpeak threshold for phocids is 3 m.

Marine Mammal Occurrence Marine mammal density estimates for the harbor porpoise, harbor seal, and gray seal are based on marine mammal monitoring observations during 2017

and 2018 CIANBRO 2018a, b. Density values were calculated from visual sightings of all marine mammals divided by the monitoring days total of 154 days and the total ensonified area
in which the sightings occurred in the 2017 and 2018 activities 0.8401 km2.
Details used for calculations are provided in Table 10 and described below.

TABLE 10MARINE MAMMAL SIGHTINGS AND RESULTING DENSITY IN THE VICINITY OF PORTSMOUTH NAVAL SHIPYARD
2017 sighting 96 days
Species
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Harbor porpoise
Harbor seal
Gray seal

Hooded and harp seals are much rarer than harbor and gray seals in the Piscataqua River, and no density information for these two species is available. To date, marine mammal monitoring for the Berth 11 Waterfront Improvements Construction project has not recorded a sighting of a hooded or harp seal in the project area Cianbro 2018ab; NAVFAC Mid-Atlantic 2018, 2019b; Navy 2019; Stantec 2020;
however, two harp seals were observed outside of the timeframe of dedicated marine mammal monitoring of Berth 11
pile-driving activities, one on May 12, 2020 and one on May 14, 2020 Stantec 2020. The Navy requested authorization of take for these two species, given the potential for occurrence, and NMFS is acting on that request.

VerDate Sep<11>2014

16:36 Jun 07, 2021

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2018 sighting 58 days
3 199
24

Take Calculation and Estimation The approach by which the information provided above is brought together to produce a quantitative take estimate is described here.
For marine mammals with calculated density information i.e., harbor porpoise, harbor seal, and gray seal, in general, estimated Level B harassment and Level A harassment take numbers are calculated using the following equation:
Estimated take = animal density
ensonified area operating days 3
However, in consideration of the prevalence of seals in the project area and in accordance with the approach utilized in IHAs previously issued to the Navy for expansion and modification of DD1, NMFS has determined that it is appropriate to increase the number of harbor seal and gray seal Level B
behavioral harassment takes. Harbor
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Total sighting
2 122
2

5
321
26

Density animal/
day/km2
0.04
2.48
0.20

seal Level B behavioral harassment takes have been adjusted upwards by multiplying the average number of harbor seals sighted per day from May through December 2020 721 sightings divided by 150 days of monitoring, or 5
harbor seals/day by the number of actual construction days 159, resulting in 795 Level B behavioral harassment takes. Gray seal Level B harassment takes have been increased utilizing the same approach 47 sightings divided by 150 days of monitoring, or 0.31 gray seals/day, resulting in 50 Level B
behavioral harassment takes.
NMFS authorized one Level B
harassment take per month for both hooded seals and harp seals for the Berth 11 Waterfront Improvements construction project in both 2018 and 2019. Following the same approach, the Navy has requested, and NMFS has authorized, one Level B harassment take each of hooded seals and harp seals per
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